Got a boot loop with the module activated.
Already pointed out by folks here, this was affecting my device severely, had nearly 30% drain in about as any minutes... After turning off NFC, changing Wifi related stuff (both "Network notification" and "Scanning always available" turned off) a...
You're hooking the wrong method, then. Look for the method that actually gets called for DownloadManager (check its source, make a test app, possibly use Xposed Method Finder, etc).
Thanks for pointing me to the tool. Although based on the source...